1. Field of the Invention
The present invention relates to a vehicle, a power supply system, and a method for controlling a power supply system. In particular, the present invention relates to a vehicle, a power supply system, and a method for controlling a power supply system using relay circuits for connecting and disconnecting a plurality of power storage devices.
2. Description of the Background Art
There has been known a power supply system including a main battery (hereinafter referred to as a first power storage device) and a sub battery (hereinafter referred to as a second power storage device) that are mounted in a vehicle and connected, in parallel with each other, to a load such as a traveling motor, via respective relay devices as switches (see, for example, Japanese Patent Laying-Open No. 2009-142102 and the like).
In the configuration of Japanese Patent Laying-Open No. 2009-142102, a capacitor is connected between a positive electrode-side line and a negative electrode-side line transmitting electric power to the load.
Further, Japanese Patent Laying-Open No. 2010-252475 discloses a power supply system having a capacitor as described in Japanese Patent Laying-Open No. 2009-142102, wherein the capacitor is discharged within a period in which an instruction for disconnection is output to a relay device, and whether or not a contact point of the relay device is welded is determined based on whether or not a voltage across the capacitor is reduced.
However, in a configuration as described in Japanese Patent Laying-Open No. 2009-142102, the second power storage device may be disconnected from the power supply system while the vehicle is traveling, due to a reduction in remaining capacity and the like. A contact point of the relay device having performed the disconnection is opened when it is operated normally. Thus, in a case where the determination of welding described in Japanese Patent Laying-Open No. 2010-252475 is performed in the configuration as described in Japanese Patent Laying-Open No. 2000-142102, the contact point of the relay device is required to be reconnected after the vehicle finishes traveling, which increases the number of times the contact point of the relay is actuated, and may lead to a shortened life of the relay device on the contrary.
The present invention has been made to solve the aforementioned problem, and one object of the present invention is to provide a power supply system having a switch for switching between supply and interruption of electric power between a power storage device and a load, in which the number of times each contact point is connected during a check for welding performed on the switch is decreased and the location of a defect can be efficiently specified.